Improvement in piston-packings



W- W. St. JOHN.

PISTON-PACKING}.

Patent-ed Feb. 29, 1876.

"WITNESSES ATTORNEYS.

NJTERS, PNIOYO-LITHOGRAPHE. WASHINGT'ON. Dv C.

\ UNITED STATES 'WILLIAM W. ST. JOHN,

OF mam, MISSOURI.

IMPROVEMENT IN PISTQN-PACKINGS.

Specification forming part of Letters Patent No. 174,3 1?, dated February 29, 1876; application filed October 2, 1875. v

To all whom it may concern.

Be it known that I, WILLIAM W. ST. J 019m, of Pisgah, in the county of Cooper and State of Missouri, have invented a new and improt'ed Piston-Packing, of which the following is a specification:

My invention consists of a piston-packing wider on-the under side than elsewhere, for the purpose of bearing the weight of the pis-, ton and piston-rod, in addition to the packing pressure, Without greater wear'than in the side of the piston, to increase the area of wearing-surface in about the same measure that the Weight of the piston tends to increase the wear, thus equalizing the wear throughout the whole surface ot' the packing. The under side of the packing is curved or rounded up'to sharp edges, as shown at D,

for admitting the steam under it to pack it to the cylinder. The packing-ring is provided with a rib, E, on its under side, which is graduated in width correspondingly to the outer or wearing surface of the ring, the rib being widest opposite the point where the area of wearing-surface is greatest, and narrowest Where it is least. This rib E fits inv a groove,

- and is held thereto by a spring,

F, in the piston-head, thus preventing any' movement of the ring on the latter. .The joint Gr of the packing is closed by a T-shaped piece, H, the head or cross piece of which fits close against the under side of the packing, J, to prevent the steam from leaking between it and the under side of the packing and escaping around the ends, and so leaking through the joint. The other or vertical part of said piece H enters the c'oincident'open slots cut in the contiguous or meeting ends of the packing-ring B, and thus keeps said ends in the same rela tive posit-ion, whatever he the expansion of the ring underv varying pressures of steam. (The packing is cast to the piston-head and also to the packing-piece H.)

I 1 am aware it is not new to construct a piston-head with a projecting peripheral rib made narrower. at the bottom than the top, for the purpose of relieving the piston of part of. the friction due to its weight by means of the lift ing action of the steam against the inclined sides of the rib. My invention is an entirely difterent conception as to object to be attained and mode or principle of operation, besides involving a different construction.

What I therefiireclaim is'- The com'bination,with a grooved piston-head, of the packing-ring B, graduated in width, and so applied that its broadest portion is on the under side of the piston-head, as shown and described, for the purpose specified.

. WM. W. ST. JOHN.

Witnesses:

J. W. ScHoLL, J. L. J OHNSON.

PATENT OFFICE; 

